A thermocouple is said to be a ‘’simple’’ temperature measurement device. With a difference in temperature between its cold junction and hot junction, you have a voltage reading that gives you an indication of the temperature being measured. But is this really a simple device? 

Well a detailed study of the thermocouple will reveal that it is not really a simple device as it seems. From the extension cables that could serve as antenna to pick up stray voltages, to ground loop problems, to advanced signal conditioning modules applied to curb noise and composition challenges in the thermocouple material, it does not appear to be a simple device in the real sense. However, the thermocouple is still a preferred device when it comes to measuring high temperatures and in certain applications where an RTD is not suitable.

How then do we use a thermocouple device successfully? Here I have itemized some practical application tips that help in making the thermocouple a success in its application:

Tip 1:
Always examine thermocouple manufacturers’ specifications for conformity to standards, specified temperature ranges, and interchangeability. These are the basics of its application.

Tip 2:
Reproducibility and interchangeability between brands of thermocouple should be examined. Errors due to thermocouple replacement are common in industry and should be avoided.

Tip 3:
Ground loops are a common problem in thermocouple applications. Use isolated signal conditioning modules to avoid ground loops.

Tip 4 :
Always use thermocouple signal conditioning modules with appropriate input filtering. This has been shown to reduce or eliminate serious noise errors.

Tip 5:
Each thermocouple wire connected to the sensing module must be at the same temperature. Module connectors should have no thermal gradients(temperature differences) across the individual connections.

Tip 6:
Thermocouple behaviour depends on the materials’ molecular structure. Environmental conditions such as stress, chemical corrosion, radiation, etc that affect molecular structure anywhere along the length of the thermocouple wire can create measurement errors.